Function coth_rrule 

pub fn coth_rrule<S: ScalarAd>(x: S, cotangent: S) -> S

Reverse rule for coth.

Examples

use chainrules::coth_rrule;

let dy = coth_rrule(0.5_f64, 1.0);
assert!((dy + 1.0 / 0.5_f64.sinh().powi(2)).abs() < 1e-12);